Method and device for preparing artificial core for petroleum geological exploration

Abstract

The present disclosure provides a method and device for preparing an artificial core for petroleum geological exploration. The method includes: step 1, establishing a relation curve between a median grain diameter of quartz sand and a permeability, determining a type and a usage amount of epoxy resin, and preparing a cementing agent according to a principle that the epoxy resin has a direct ratio with a specific surface; step 2, based on a method of controlling a core permeability, preparing benchmark sand with quartz sand of different grain sizes in a certain ratio, fabricating a low-permeability core by adjusting a ratio of the benchmark sand to fine sand, and fabricating a high-permeability core by adjusting a ratio of the benchmark sand to coarse sand; step 3, separately and proportionally weighing quartz sand of different grain diameters and putting them into a magnetic tray, manually mixing and agitating for later use.

What is claimed is: 
     
         1 . A method for preparing an artificial core for petroleum geological exploration, comprising the following steps:
 step 1, establishing a relation curve between a median grain diameter of quartz sand and a permeability, determining a type and a usage amount of epoxy resin, and preparing a cementing agent according to a principle that the epoxy resin has a direct ratio with a specific surface;   step 2, based on a method of controlling a core permeability, preparing benchmark sand with quartz sand of different grain sizes in a certain ratio, fabricating a low-permeability core by adjusting a ratio of the benchmark sand to fine sand, and fabricating a high-permeability core by adjusting a ratio of the benchmark sand to coarse sand;   step 3, separately and proportionally weighing quartz sand of different grain diameters and putting them into a magnetic tray, and manually mixing and agitating for later use, wherein since agitating frequency, times and uniformity degree for per capita have a great influence on porosity and permeability values of an artificial core during stirring, and a quartz sand mixing agitator is employed to avoid man-made nonuniform agitation;   step 4, adding a clay mineral, wherein a clay mineral in a natural rock core plays an important role on a structure and physical properties of the rock core; according to a principle of physical simulation similarity criterion, a certain amount of clay mineral is added to an artificial core; and a special method of adding the clay mineral is used to avoid the clay mineral from being covered with the epoxy resin; and   step 5, preparing an artificial core: preparing a slightly oil-wet core by diluting silicone oil which is 10% by weight of a sand mold with 20 times petroleum ether, evenly agitating the diluted silicone oil with 40 to 70-mesh quartz sand, 70 to 140-mesh quartz sand and 140 to 200-mesh quartz sand, volatilizing at room temperature for 20 h, then putting the mixed quartz sand into an electrothermal blowing dry box, warming according to temperature programming of 60° C., 80° C., 100° C. and 120° C., each for 2 h and at intervals of 1 h, keeping a constant temperature at 120° C. for 2 h and then turning off the dry box for natural cooling to the room temperature, wherein the warming process guarantees that an oil film on the surface of sand grains does not burst during rapid warming; and preparing neutral and water-wet cores with untreated quartz sand and epoxy resin, 20% dibutyl phthalate as a flexibilizer and 7% ethanediamine as a curing agent, wherein the prepared artificial cores have neutral and slightly oil-wet properties.   
     
     
         2 . The method for preparing an artificial core for petroleum geological exploration according to  claim 1 , wherein during sand filling, sand is added each time in an appropriate amount and at an appropriate thickness to avoid local compaction, and the sand added each time needs to be carded and flattened. 
     
     
         3 . The method for preparing an artificial core for petroleum geological exploration according to  claim 1 , wherein a specific operation method in step 4 comprises:
 (1) fully agitating the quartz sand with the epoxy resin in a certain proportion and putting a resulting mixture into a prepared evacuator; (2) saturating the mixture with a water-based clay suspension of a known composition such that the sand mold is in full contact with or adsorbs the clay in the water; then removing the water-based clay suspension, repeating the above process for a plurality of times, and finally drying the water-based clay suspension and weighing the residual clay to obtain an amount of the adsorbed clay; and (3) putting suction-filtered sand mold into a mold, and pressurizing and drying.   
     
     
         4 . The method for preparing an artificial core for petroleum geological exploration according to  claim 1 , wherein a drum, an agitating impeller and a main box of the agitator in step 3 are all controlled to rotate in different directions such that the quartz sand is agitated therein in a three-dimensional rotational manner, avoiding nonuniform manual agitation of the quartz sand and guaranteeing that porosities, permeability values, pore structures and rock grain size distributions at all points of the artificial core are respectively consistent. 
     
     
         5 . A device for preparing an artificial core for petroleum geological exploration, applied to the method for preparing an artificial core for petroleum geological exploration according to  claim 1 . 
     
     
         6 . The device for preparing an artificial core for petroleum geological exploration according to  claim 5 , wherein during sand filling, sand is added each time in an appropriate amount and at an appropriate thickness to avoid local compaction, and the sand added each time needs to be carded and flattened. 
     
     
         7 . The device for preparing an artificial core for petroleum geological exploration according to  claim 5 , wherein a specific operation method in step 4 comprises:
 (1) fully agitating the quartz sand with the epoxy resin in a certain proportion and putting a resulting mixture into a prepared evacuator; (2) saturating the mixture with a water-based clay suspension of a known composition such that the sand mold is in full contact with or adsorbs the clay in the water; then removing the water-based clay suspension, repeating the above process for a plurality of times, and finally drying the water-based clay suspension and weighing the residual clay to obtain an amount of the adsorbed clay; and (3) putting suction-filtered sand mold into a mold, and pressurizing and drying.   
     
     
         8 . The device for preparing an artificial core for petroleum geological exploration according to  claim 5 , wherein a drum, an agitating impeller and a main box of the agitator in step 3 are all controlled to rotate in different directions such that the quartz sand is agitated therein in a three-dimensional rotational manner, avoiding nonuniform manual agitation of the quartz sand and guaranteeing that porosities, permeability values, pore structures and rock grain size distributions at all points of the artificial core are respectively consistent. 
     
     
         9 . The device for preparing an artificial core for petroleum geological exploration according to  claim 5 , comprising a screening assembly, an agitating assembly, an evacuating assembly and a drying assembly. 
     
     
         10 . The device for preparing an artificial core for petroleum geological exploration according to  claim 6 , comprising a screening assembly, an agitating assembly, an evacuating assembly and a drying assembly. 
     
     
         11 . The device for preparing an artificial core for petroleum geological exploration according to  claim 7 , comprising a screening assembly, an agitating assembly, an evacuating assembly and a drying assembly. 
     
     
         12 . The device for preparing an artificial core for petroleum geological exploration according to  claim 8 , comprising a screening assembly, an agitating assembly, an evacuating assembly and a drying assembly. 
     
     
         13 . The device for preparing an artificial core for petroleum geological exploration according to  claim 5 , wherein the agitating assembly is an agitator; and a drum, an agitating impeller and a main box of the agitator are all controlled to rotate in different directions such that quartz sand is agitated therein in a three-dimensional rotational manner. 
     
     
         14 . The device for preparing an artificial core for petroleum geological exploration according to  claim 6 , wherein the agitating assembly is an agitator; and a drum, an agitating impeller and a main box of the agitator are all controlled to rotate in different directions such that quartz sand is agitated therein in a three-dimensional rotational manner. 
     
     
         15 . The device for preparing an artificial core for petroleum geological exploration according to  claim 7 , wherein the agitating assembly is an agitator; and a drum, an agitating impeller and a main box of the agitator are all controlled to rotate in different directions such that quartz sand is agitated therein in a three-dimensional rotational manner. 
     
     
         16 . The device for preparing an artificial core for petroleum geological exploration according to  claim 8 , wherein the agitating assembly is an agitator; and a drum, an agitating impeller and a main box of the agitator are all controlled to rotate in different directions such that quartz sand is agitated therein in a three-dimensional rotational manner. 
     
     
         17 . The device for preparing an artificial core for petroleum geological exploration according to  claim 5 , wherein the screening assembly comprises a 20 to 80-mesh sieve mesh and a vibration motor; the evacuating assembly comprises a vacuum pump and a suction filtration pump; and the drying assembly comprises an electrothermal blowing dry box, a constant temperature box and a cooling box. 
     
     
         18 . The device for preparing an artificial core for petroleum geological exploration according to  claim 6 , wherein the screening assembly comprises a 20 to 80-mesh sieve mesh and a vibration motor; the evacuating assembly comprises a vacuum pump and a suction filtration pump; and the drying assembly comprises an electrothermal blowing dry box, a constant temperature box and a cooling box. 
     
     
         19 . The device for preparing an artificial core for petroleum geological exploration according to  claim 7 , wherein the screening assembly comprises a 20 to 80-mesh sieve mesh and a vibration motor; the evacuating assembly comprises a vacuum pump and a suction filtration pump; and the drying assembly comprises an electrothermal blowing dry box, a constant temperature box and a cooling box. 
     
     
         20 . The device for preparing an artificial core for petroleum geological exploration according to  claim 8 , wherein the screening assembly comprises a 20 to 80-mesh sieve mesh and a vibration motor; the evacuating assembly comprises a vacuum pump and a suction filtration pump; and the drying assembly comprises an electrothermal blowing dry box, a constant temperature box and a cooling box.